Oral care compositions generally refer to dentifrice and dental adhesives. Dentifrice formulations generally contain dentally acceptable abrasive, humectant, water, and water-soluble polymer which serves as a thickener and binder for the ingredients. A variety of other ingredients such as flavors, color, vitamins, antiplaque, anti-tarter, breath freshener, color, sweeteners, preservatives and fluoride are also used at low levels. Glycerol and sorbitol (usually as an aqueous solution) are the most commonly used humectants for dentifrice, and depending on the characteristics desired in the product, polyethylene glycol or propylene glycol may be incorporated as well. Four types of dentifrice are widely produced: 1) cream, 2) transparent or translucent gel, 3) stripes of cream and gel, and 4) dry powders.
The thickeners or binders used for dentifrice are carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), silica, magnesium aluminum silicate, carrageenan, xanthan, guar, alginate, polyacrylic acids, salts of polyacrylic acids, polymers of ethylene oxide, copolymer of ethylene oxide and propylene oxide, processed euchemia seaweed (PES), starch, starch derivatives, pectin, and agar.
In the manufacturing process for dentifrice, incorporation of a dry water-soluble binder polymer into the composition often presents difficulties because of the tendency for lump formation when the dry polymers are added to and dispersed in aqueous systems. This increases the time required to obtain uniform hydration or uniform dispersion of the binder polymer. And sometimes, portions of the polymer could remain in dentifrice in partially hydrated gel form. This can not only affect dentifrice shelf stability and rheology but would also make dentifrice aesthetically unappealing. A re-occurring problem in the dentifrice industry is to make a polymer that is universally dispersible regardless of the environment in which it is to be used. Making a polymer dispersible based on a particular formulation has been done prior to the present invention but that makes a polymer formulation specific. Consequently, there is a need in the industry for a method of incorporating water-soluble binder polymers into dentifrice formulations universally which lead to dust-free and lump-free products, rapid viscosity development and reduced batch preparation time, and allow convenient handling of the binder.
U.S. Pat. No. 5,869,029 discloses a dentifrice composition using an agglomerated composition of a water-soluble polymer at least partially agglomerated by treatment with at least one polyol. U.S. Pat. No. 3,396,034 discloses a process of converting a hard to disperse particulate cellulose ether material or vegetable gum into a readily dispersible, dust-free particulate material by subjecting fine particles to water spray in an amount sufficient to cause superficial hydration. U.S. Pat. No. 4,557,938 discloses a process for preparing a dispersible agglomerated vegetable gum/carrier particles by dry blending particulate carrier, such as starch and the vegetable gum in a fluid bed dryer. The fluidized vegetable gum and starch particles are sprayed with water to wet the surface of the particles to cause agglomeration. U.S. Pat. No. 3,455,714 discloses the agglomerating of a water-soluble polymer with water-soluble cellulose ether that does not have a tendency to agglomerate when added to water. Japanese Patent No. 93075369 B discloses a method of spraying water onto water-soluble powdery paste under fluidized state and drying the formed granules. The starting powdery paste can be hydroxypropylcellulose or carboxymethylcellulose among other polymers.
None of the above patents discloses the use of water or aqueous polymer agglomerated water-soluble or water-swellable polymer in oral care compositions.